Some analyte sensors utilize analyte responsive enzymes to directly or indirectly detect analytes. These enzymes are typically immobilized or encapsulated in or between one or more membranes or layers of the analyte sensor. In vivo sensors, which are in contact with blood and tissue, the sensor and its analyte responsive enzyme preferably is provided sterilized. Commonly used methods of sterilization such as exposing the device to ethylene oxide, or high energy radiation, for example gamma rays, electron beams, ultraviolet light, or x-rays is undesirable for analyte responsive enzymes. The high-energy radiation can affect all of the sensor's components by creating free radicals, which can chemically change one or more of the sensor's components, including the enzyme.